The present invention generally relates to a system for testing the vibrational imbalance of a mechanism, such as a diesel V-8 engine, and more particularly relates to an apparatus for permitting the mechanism to vibrate under test conditions, such that the imbalance can be determined and measured.
Internal combustion engines must be balanced for maximum, trouble-free life. That is, the vibration of an internal combustion engine, resulting from rotation of its parts during operation, must be within an acceptable tolerance. Otherwise the vibration will be sufficient to cause excessive wear, metal fatigue and failure.
To achieve this balance in the mass production of engines, the individual components of the rotating assembly, e.g., the crank shaft, pistons, piston rods, flywheel and starter pulley, are machined to precise dimensions and individually balanced, both statically and dynamically. Each assembled engine is also tested, and if necessary, the imbalance is reduced to within an acceptable level.
Engine imbalance is generally reduced by adding weight to or subtracting weight from the flywheel or starter pulley of the engine, in amounts and at locations to counteract the imbalance. To determine amount and location, the velocity of the vibration is monitored in the planes of the flywheel and starter pulley to identify the magnitude and location of discrete front and rear imbalance torques.
For accurate measurements of imbalance, the engine vibration must not be unduly influenced or dampened by the test system. That is, the apparatus upon which the engine is mounted must permit substantially free, uninhibited vibration. This requires that the engine mount or test stand add only a minimum quantity of parasitic damping mass to the engine under investigation.
Minimum influence by the test stand is particularly difficult to achieve with a diesel V-8 engine. This is due to the fact that a diesel V-8 engine vibrates substantially in a horizontal plane and any effort to support the engine tends to inhibit vibration in that plane.